1. Technical Field
The present invention relates generally to an apparatus for deploying satellites in orbit and, more particularly, to a satellite dispenser that is selectively configurable to deploy multiple satellites from a single launch vehicle and which includes a single piece, integrally formed tubular dispenser shell.
2. Discussion
Launch vehicles used to deploy satellites in a predetermined orbit about the Earth commonly include a device that couples the satellites to the launch vehicle and that is adapted to release the satellites in response to a control signal. Recent technological advancements and market forces have changed the focus of satellite deployment from payloads of a single large satellite to multiple smaller satellites. More particularly, advancements in technology relating to satellite and launch vehicle design as well as orbital deployment techniques have allowed smaller industries and companies to enter the satellite market. Global network coverage provided by an array of small satellites is coveted by the communications industry and the market for scientific payloads is increasing in commercial significance.
The increased demand for small satellite deployment has given rise to previously unaddressed concerns regarding integration of multiple satellites on a single launch vehicle, as well as the continuing need to maximize the accuracy of satellite deployment. Existing deployment devices designed for a multiple satellite payload have proven to lack the desired flexibility in integrating the satellites with the launch vehicle. Rather, commonly used deployment devices accommodate a predetermined and limited number of satellites. These devices also fail to adequately accommodate the variety of sizes and weights of satellite payloads. Thus, a need exists for a multiple satellite dispenser that affords greater flexibility in the number, size, and weight of satellites which can be accommodated thereon for deployment.
An additional drawback with present day satellite deployment devices is the complexity, overall weight and cost of manufacturing of such devices. Present day satellite dispensers typically incorporate an elongated, multi-piece dispenser shell which is used to support a plurality of satellites thereon. For example, the apparatus of U.S. Pat. No. 5,884,886, while being well received in the industry, nevertheless incorporates two large, independent, tubular components which are secured together via a large diameter aluminum connecting ring. This connecting ring is also sometimes referred to in the art as a xe2x80x9ckick ringxe2x80x9d.
The connecting ring is used to attach an elongated tubular post portion and a frusto-conical base portion together to form the dispenser shell which is used to support the satellites thereon. Since this structure is therefore quite large in diameter and length (often up to 35 feet in length (about 10.5 meters) and about 17 feet in diameter (about five meters) at the bottom of the base portion), this necessitates a large diameter connecting ring. The connecting ring can range in diameter from about three-eight feet (about one-three meters) and weigh in the range of 100 lbs-1500 lbs depending upon its overall dimensions.
As will be appreciated, manufacturing a dispenser having such large independent components involves significant and expensive manufacturing efforts. The large connecting ring and the two independent tubular members which it couples must be moved into precise alignment by large, expensive tooling. Tooling is also required to precisely locate and drill joint holes. Labor is required to drill and install fasteners for securing the three components together. Labor is also needed for fabricating and inspecting each of the large component parts. The cost of the aluminum connecting ring alone is a significant factor in the overall cost of manufacture of the satellite dispenser. Accordingly, the tooling and labor involved in manufacturing a multi-piece dispenser shell represents a major component of the overall cost of the satellite dispenser.
In addition to manufacturing complexities, the overall weight of the satellite dispenser is also an important factor which can limit the number of satellites that are carried into orbit by a launch vehicle. Since the total payload which must be considered is the weight of all of the satellites being carried on the dispenser plus the weight of the dispenser itself, it is critically important to minimize the weight of the dispenser without compromising structural rigidity and strength. Minimizing the weight of the dispenser helps to reduce the amount of fuel needed by the launch vehicle to propel any given number of satellites supported on the dispenser into orbit, or to enable larger and heavier satellites to be carried on the dispenser for a given amount of fuel.
Finally, it would be highly preferred, for structural strength and rigidity, to provide a dispenser apparatus which incorporates a single piece, tubular dispenser shell for supporting the satellites thereon. A single piece dispenser shell would provide even greater structural rigidity and resistance to axial bending forces while eliminating the need for a connecting ring, thus reducing its overall weight substantially.
The present invention provides a satellite dispenser adapted to deploy a variety of multiple satellite payloads in a simple and operationally efficient manner. The dispenser is adapted to be coupled to a launch vehicle which carries the satellite dispenser into orbit. Once into orbit, each satellite carried by the dispenser can be deployed at the desired point of travel in orbit.
In one preferred embodiment the present invention includes a post having a longitudinal axis, a base portion for coupling the post to a launch vehicle, and a plurality of attachment assemblies coupled to the post and having attachment assemblies for deployably (i.e., releasably) coupling one or more satellites to the post portion. The attachment assemblies define multiple points of attachment for each satellite carried by the post portion of the dispenser.
In another preferred embodiment the satellite dispenser comprises a single piece, integrally formed tubular dispenser shell for supporting one or more satellites thereon. The tubular shell includes a post portion and a base portion. The post portion includes a plurality of attachment assemblies for supporting one or more satellites independently thereon. The single piece tubular shell eliminates the need for a connecting ring for coupling the post and base portions together, thereby substantially reducing the cost and simplifying the manufacture of the dispenser shell. Eliminating the connecting ring also significantly reduces the overall weight of the satellite dispenser.
In the preferred embodiment the single piece tubular dispenser shell is manufactured from high modulus, composite graphite epoxy fibers which provide very high structural rigidity and stiffness in the longitudinal direction of the post portion. This serves to significantly improve the bending stiffness of the post portion. The resulting dispenser shell is extremely high in structural strength yet lighter in weight than dispensers incorporating two or more independent tubular or conical portions coupled by a connecting ring. The savings in weight increases the payload capacity of a launch vehicle carrying the satellite dispenser and its satellites into orbit.
In another alternative preferred embodiment, the satellite dispenser of the present invention incorporates a one-piece tubular dispenser shell having three conical sections each having a different degree of taper. The different degrees of taper serve to further enhance the overall structural strength of the structure as well as to enable a plurality of satellites to be more compactly supported on the structure.